CN1224701C - High-effective aciduric liquifying saccharifyig enzyme, its preparation method and application - Google Patents

Abstract

An acid-resistant liquefaction glucoamylase and its preparation method and application, which are characterized in that genetic engineering technology is used to carry out genetic breeding, and the fungus TR12 containing multiple copies of acid-resistant α-amylase and glucoamylase fusion genes is obtained as a practical strain. Technology production enzyme preparation and liquefaction and saccharification process integration process is realized. The acid-resistant α-amylase activity in the enzyme preparation is measured with reference to the industry standard QB1805.1-93. The acid-resistant α-amylase activity is 500-1000U/g, and the glucoamylase The activity is determined by reference to QB1805.2-93. The activity of glucoamylase is 20000~50000U/g. The liquefied glucoamylase is mainly used for starch hydrolysis in starch sugar products and starch hydrolysis in alcohol, amino acid, organic acid and antibiotic fermentation industries. It has the simultaneous liquefaction and saccharification process, low energy consumption, low product viscosity, good filterability, high yield, stable quality, no three waste pollution, and greatly reduces production cost and labor intensity.

Description

Acid-resistant liquefaction glucoamylase and its preparation method and use

1. Technical field

The invention relates to an acid-resistant liquefaction glucoamylase and a preparation method thereof, belonging to the field of enzymatic hydrolysis and utilization of starch raw materials.

2. Background technology

The enzymatic decomposition of starchy raw materials generally involves the synergistic action of two enzymes, α-amylase and glucoamylase, to complete the liquefaction and saccharification process of starch. α-amylase (α-amylase, EC3.2.1.1.) is an amylase with endolytic activity, which can cut α-1,4 glycosidic bonds from the inside under neutral pH conditions, and hydrolyze starch into Maltose, maltooligosaccharides and a small amount of glucose; the full name of glucoamylase (glucoamylase, EC3.2.1.3.) is an exonuclease that can cut α- 1,4 and α-1,6 glycosidic bonds, the final product of the reaction is glucose molecules.

Since the optimal reaction pH of α-amylase and glucoamylase is different, neutral amylase and acid glucoamylase cannot be used at the same time, and the liquefaction and saccharification of starchy raw materials need to be completed by two processes; although there are α-amylases on the market The compound enzyme of enzyme and glucoamylase appears. Based on the above reasons, the activity of α-amylase becomes extremely low or even loses its activity in the acidic environment of the fermentation process such as brewing. Although there are also acid-resistant α-amylases produced by bacteria. , but only a few foreign companies produce, and the price is high, which is far from meeting the needs of the market.

3. Contents of the invention

The object of the present invention is to provide an acid-resistant liquefaction glucoamylase and its preparation method in view of the deficiencies in the prior art, which is characterized in that genetic engineering technology is used to carry out genetic breeding to obtain a fusion enzyme containing multiple copies of acid-resistant α-amylase and glucoamylase Genetic special mold TR12 strain (Journal of The Institute of Brewing, Vol.105, No.9, 1999), the inventor aims to use this genetically engineered strain as a practical strain to produce enzyme preparations and starch liquefaction and saccharification through fermentation engineering technology Process integration process realization.

The purpose of the present invention is achieved by the following technical measures. The parts of raw materials described herein are parts by weight unless otherwise specified.

Acid-resistant liquefaction glucoamylase and preparation method thereof:

The seed medium is made of starch, inoculated with the mold TR12 strain obtained by genetic engineering breeding, and the seeds are obtained through cultivation. The seeds are inserted into the fermentation medium made of starch, under aeration, at a temperature of 30-35°C, and prepared Acid-resistant liquefied glucoamylase, and then extracted to obtain enzyme preparations.

(1) Bacteria culture on inclined plane

Take engineering bacteria TR12 to preserve strains (or freeze-dried tubes, or sand tubes, or preserved slopes), inoculate the selected slope medium, and cultivate at a temperature of 30-35°C for 7-10 days, and select slopes with uniform surface growth and thick spore layer The colonies are transplanted into starch medium again, and cultivated at a temperature of 30-35°C for 5-7 days to obtain slant strains, which can be stored at a temperature of 4°C for 15-30 days.

(2) Seed cultivation

Mix the starchy raw materials of the seed culture medium with water evenly, heat and stir until the starch is gelatinized, after cooling, add α-amylase to liquefy, filter with double-layer gauze, add corn steep liquor, and constant volume. Packed in Erlenmeyer flasks. Sterilize at a temperature of 118-122° C. for 20-25 minutes, inoculate after cooling, and cultivate at a temperature of 32-35° C. for 20-30 hours on a revolving shaker at 120-220 r/min to obtain seeds.

(3) Shake flask fermentation Fermentation process without feeding

Add water to gelatinize the starchy raw materials of the fermentation medium, liquefy, filter, add corn steep liquor, adjust the pH, constant volume, divide into conical flasks, sterilize at 118-122°C for 20-30 minutes, cool, The cultivated seed culture is added according to the inoculum amount of 10-20%, and then cultivated on a 120-220r/min rotary shaker at a temperature of 30-32°C for 3-4 days to obtain a fermentation liquid product.

(4) Shake flask fermentation Fed-batch fermentation process

The preparation of the fermented base material medium is the same as the fermentation medium described in the fermentation process without feeding, and the base medium is divided into Erlenmeyer flasks. Sterilize at a temperature of 118-122°C for 20-30min. After cooling, add the cultured seeds according to the inoculum amount of 10-20%. On a rotary shaker at 120-220r/min, under the conditions of 10-20% feeding amount each time and 1-3 feeding times (feeding medium, only the carbon source concentration is 3-5 times that of the base material, and other ingredients Same), cultivated at 30-32°C for 4-6 days to obtain the fermentation broth product.

(5) Enzyme Extraction

The above-mentioned fermentation liquid product is put into a centrifuge, centrifuged at 3000-3500 rpm for 10-20 minutes, washed, and the supernatant liquid is filtered and combined to obtain a crude enzyme liquid. The crude enzyme liquid is obtained under the conditions of a vacuum of 0.07-0.09Mpa and a temperature of 40-45°C to obtain a concentrated enzyme liquid. Adjust the pH of the concentrated enzyme solution to 3.5-4.5, add 10-20g of cornstarch to each liter of enzyme solution, stir evenly to make the enzyme and starch fully adsorbed, slowly add 2-2.5 times of refrigerated ethanol at a temperature of 10-20°C, and Stir while adding, you can see the precipitation of the enzyme. After the sediment is centrifuged, the obtained enzyme sludge is put into a vacuum drying oven, and dried at a vacuum degree of 0.07-0.09Mpa and a temperature of 40-45°C for 3-4 hours to obtain a finished crude enzyme preparation.

The acid-resistant α-amylase activity in the enzyme preparation is measured with reference to the industry standard QB1805.1-93, the acid-resistant α-amylase activity is 500-1000U/g, the glucoamylase activity is measured with reference to QB1805.2-93, and the glucoamylase activity is 20000～50000U/g, optimum temperature 50-60℃, pH=4.0-5.0, best thermal stability at 50℃, K ⁺ , Na ⁺ , Ca ²⁺ , Mg ²⁺ and other metal compounds can be used as enzyme preparation activity protector or accelerator. The liquefying glucoamylase is mainly used for starch hydrolysis in starch sugar products and starch hydrolysis in the fermentation industry of alcohol, amino acid, organic acid and antibiotics. The acid-resistant liquefying saccharifying enzyme preparation of the present invention is compared with the existing enzyme preparation indicators, see the table for details 1.

The present invention has the following advantages:

1. It fills the gap in my country's acid-resistant α-amylase varieties and realizes the integration of liquefaction and saccharification processes in acidic environments. It can not only replace imports, but also earn foreign exchange through exports, contributing to the development of my country's national economy.

2. This product has a wide range of applications, a broad market prospect, and is of great significance to the protection of the environment and ecology.

3. Using acid-resistant liquefaction and saccharification enzyme, pH=4.0-5.0, low liquefaction acidity, simultaneous liquefaction and saccharification process, low viscosity, low energy consumption, good filterability and high yield. For example, per ton of distiller's residue and enzyme re-fermentation, it is expected to produce 20 kilograms of 50° wine more, and the economic benefit is remarkable.

4. It can reduce the production cost and labor intensity of enterprises using this product, increase productivity, and promote traditional industries to a new level.

4. Description of drawings

Figure 1 is a flow chart for the preparation of high-efficiency acid-resistant liquefaction glucoamylase.

5. Specific implementation

The present invention is specifically described below through the examples, it is necessary to point out that the present examples are only used to further illustrate the present invention, but can not be interpreted as limiting the protection scope of the present invention, those skilled in the art can according to the above-mentioned The contents of the present invention make some non-essential improvements and adjustments.

Embodiment 1 (preparation of enzyme preparation)

1) Bacteria culture on slant

Take the preserved strain of engineered bacteria TR12 and inoculate the selection slant medium (KCl 2g/L, K ₂ HPO ₄ 1g/L, MgSO ₄ 7H ₂ O 0.5g/L, FeSO ₄ 7H ₂ O 0.02g/L, Sugar 1mol/L, acetamide 10mM, CsCl 15mM, agar 15g/L), cultured at 32°C for 7 days, transplanted into starch slant medium (corn starch 20g/L, KNO ₃ 2g/L, MgSO ₄ 7H ₂ O 1.2g/L, KH ₂ PO ₄ 2.7g/L, agar powder 20g/L, pH 5.0), cultured at 32°C for 7 days to obtain slant strains.

2) Seed cultivation

Add water to the seed medium (corn flour 60g/L, corn steep liquor 20g/L, soybean flour 20g/L) starchy raw materials and mix evenly, heat and stir until the starch is gelatinized. After cooling, add α-amylase to liquefy, filter with double-layer gauze, add corn steep liquor components, and make to volume. Pack 250-ml Erlenmeyer flasks according to 50ml per bottle, stopper the mouth of the bottle with 8 layers of gauze, and wrap it with kraft paper. Sterilize at 121°C for 20 minutes, inoculate after cooling, and then culture at 32°C for 25 hours on a rotary shaker at 210 r/min.

3) Shake flask fermentation

Add water to gelatinize and liquefy the starchy raw materials of the fermentation medium (corn flour 50g/L, corn steep liquor 20g/L, soybean flour 20g/L, bran 30g/L, citric acid to adjust the pH value to 3.5-4.0), filter, Finally, add corn steep liquor, adjust the pH, constant volume, and pack into 250-ml Erlenmeyer flasks according to 50ml. Sterilize at a temperature of 121°C for 20 minutes, cool down, add the cultured seed culture at a 10% inoculum size, and then cultivate at a temperature of 32°C for 4 days on a 210r/min rotary shaker to obtain a fermentation broth product.

4) Enzyme Extraction

Add the above-mentioned fermentation broth product into a centrifuge, centrifuge at 3500rpm for 15 minutes, wash, filter the supernatant through gauze, and combine to obtain crude oil containing acid-resistant α-amylase activity of 20.9U/ml and glucoamylase activity of 786U/ml. The enzyme solution was concentrated in a water bath with a vacuum degree of 0.09Mpa and 45°C to obtain a concentrated enzyme solution containing an acid-resistant α-amylase activity of 202.9U/ml and a glucoamylase activity of 7540U/ml. Concentrate the enzyme solution to adjust the pH to 3.5, add 1% corn flour, stir evenly, slowly add 2.2 times of refrigerated ethanol at 10-20°C, stir while adding, precipitate the enzyme precipitate, and put the enzyme sludge into a vacuum drying oven after centrifugation , dried at a vacuum degree of 0.09Mpa and a temperature of 45°C for 3 hours, and the dried product was a finished crude enzyme preparation containing an acid-resistant α-amylase activity of 863U/g and a glucoamylase activity of 30736U/g.

Embodiment 2 (preparation of enzyme preparation)

1) Bacteria culture on slant

With embodiment 1.

2) Seed cultivation

With embodiment 1.

3) Shake flask fermentation

Add water to gelatinize and liquefy the starchy raw materials of the fermentation medium (corn flour 50g/L, corn steep liquor 20g/L, soybean flour 20g/L, wheat bran 30g/L, pH value 3.5 with citric acid), and filter. Pack 800mL into 3000ml Erlenmeyer flasks. Sterilize at 122°C for 25 minutes. After cooling, add the cultivated Erlenmeyer flask seed material according to 15% inoculum amount. Cultivate on a 160r/min rotary shaker at 32°C, and feed once at 20% at 32 hours and 80 hours respectively (feed medium, only the carbon source concentration is 3 times that of the base material, and the other ingredients are the same) , after culturing for 5 days, a fermentation broth product was obtained.

4) Enzyme Extraction

The extraction method was the same as that in Example 1. After the above-mentioned fermentation broth product was centrifuged, washed, filtered, concentrated, and dried, a finished crude enzyme preparation containing an acid-resistant α-amylase activity of 925 U/g and a glucoamylase activity of 35142 U/g was obtained.

Embodiment 3 (preparation of enzyme preparation)

1) Bacteria culture on slant

With embodiment 1.

2) Seed cultivation

With embodiment 1.

3) Shake flask fermentation

Add water to gelatinize and liquefy the starchy raw materials of the fermentation medium (corn flour 50g/L, corn steep liquor 20g/L, soybean flour 20g/L, wheat bran 30g/L, pH value 3.5 with citric acid), and filter. Dispense 500ml into 3000-ml Erlenmeyer flasks. Sterilize at a temperature of 118°C for 30 minutes. After cooling, add the cultivated Erlenmeyer flask seed material according to 20% inoculum amount. Cultivate on a 160r/min rotary shaker at 32°C, and feed once at 15% at 32 hours, 64 hours, and 96 hours respectively (feed medium, only the carbon source concentration is 5 times that of the base material, other The ingredients are the same), and after culturing for 6 days, the fermentation broth product is obtained.

4) Enzyme Extraction

The extraction method was the same as that in Example 1. After the above-mentioned fermentation broth product was centrifuged, washed, filtered, concentrated, and dried, a finished crude enzyme preparation containing acid-resistant α-amylase activity of 711U/g and glucoamylase activity of 21754U/g was obtained.

Application example 1 (preparation of glucose syrup)

Add water to cornstarch to make starch milk with a concentration of 300-320g/L, adjust the starch milk to pH 4.5-4.6 with HCl aqueous solution, and add 500mg of calcium chloride and 10mg of sodium chloride per kilogram of dry starch. Add 8U/g starch (calculated by acid-resistant α-amylase activity) made by our laboratory, and keep it warm at 60-65°C for about 60 minutes until it turns brownish orange when tested with iodine solution, and the liquefaction purity is 20-22%. Then lower the temperature to 55°C, and then add self-made enzyme preparation 100U/g starch (calculated by glucoamylase activity) to continue saccharification for about 30 hours, and measure the degree of saccharification to 96%-98% by heat preservation. Add 1%-1.5% activated carbon, heat to 80°C-90°C for decolorization for 30min, and adjust the pH to 4.0-4.2. After filtration and ion exchange resin treatment, pure glucose syrup can be obtained.

Application example 2 (alcoholic fermentation)

Weigh 50g of corn flour, add 2.5 times the amount of water to adjust the slurry, adjust the pH value to 4.6, boil for 2 minutes, cool to 60°C, add 10U/g starch (acid-resistant α-amylase activity) homemade enzyme Liquefaction and saccharification at 60°C for 15 minutes, then cooling down to 50°C, adding 150U/g starch (calculated by glucoamylase activity) self-made enzyme solution to continue saccharification for 30 minutes until dilute iodine solution turns brown. Put the saccharification solution into a 500-ml Erlenmeyer flask, replenish the saccharification solution to 225g, add 1g of dry yeast, and ferment for 3 days at room temperature at 25°C. Distill to obtain 80ml of alcohol with a concentration of 28.3% v/v, and the yield of ethanol is 45.28ml/100g starch.

Application example 3 (alcoholic fermentation)

Weigh 50g of corn flour, add 2.5 times the amount of water to adjust the slurry, adjust the pH value to 4.6, directly add 10U/g starch (acid-resistant α-amylase activity) self-made enzyme solution, liquefy and saccharify at 60°C for 1h , and then lower the temperature to 50°C, add 80U/g starch (calculated by glucoamylase activity) homemade enzyme solution and continue saccharification for 30min until dilute iodine solution turns brown. Put the saccharification solution into a 500-ml Erlenmeyer flask, replenish the saccharification solution to 225g, add 1g of dry yeast, and ferment for 4 days at room temperature at 25°C. Distill to obtain 80ml of alcohol with a concentration of 30.9% v/v, and the yield of ethanol is 49.44ml/100g starch.

Table 1 Comparison of acid-resistant liquefaction saccharification enzyme preparation of the present invention with existing enzyme preparation indicators: Similar Technologies (Products) Production status (reference) optimum pH Product reference specification (U/g) Product reference price (yuan/kg) Main application areas domestic foreign General alpha-amylase Production Production 6-7 1200-2500 10-20 starch processing Thermostable α-amylase Production Production 6-7 1200-2500 15-25 Alcohol industry Acid resistant alpha-amylase (food grade) none Production 5-6 1000-1500 50-400 brewing industry Acid resistant alpha-amylase (analytical grade) none Production 4-6 10000 750 test analysis Acid-resistant liquefaction glucoamylase (industrial grade) of the present invention Production none 4-5 Acid resistance α-amylase activity 500-1000 50 Starch processing, alcohol industry, liquor industry, fruit juice manufacturing, pharmaceutical industry, feed industry, environmental protection, etc. Glucoamylase activity 20000-50000

Claims (3)

1. An acid-resistant liquefaction glucoamylase prepared by the following method is characterized in that corn flour, corn steep liquor, soybean flour starch are made into seed culture medium, inoculated with the mold TR12 bacterial strain gained by genetic engineering breeding, and produced through cultivation The seeds are obtained, the seeds are inserted into the fermentation medium made of starch, under aeration, at a temperature of 30-35°C, an acid-resistant liquefaction glucoamylase is obtained, and then the enzyme preparation is obtained by extraction. Among them, the acid-resistant α-amylase activity is determined by referring to the industry standard QB1805.1-93, and the acid-resistant α-amylase activity is 500-1000U/g, and the glucoamylase activity is measured by referring to QB1805.2-93, and the glucoamylase activity is 20000-50000U /g. 2. According to the preparation method of the acid-resistant liquefaction glucoamylase according to claim 1, it is characterized in that: (1) Bacteria culture on inclined plane Take engineering bacteria TR12 to save the strain, inoculate the selected slant medium, and cultivate it at a temperature of 30-35°C for 7-10 days, select a slant colony with uniform surface growth and a thick spore layer, and transplant it into a starch medium again, and cultivate it at a temperature of 30-35°C. Cultivate for 5-7 days at ℃ to obtain slant strains, (2) Seed cultivation Mix the starchy raw materials of the seed medium with water evenly, heat and stir until the starch is gelatinized, after cooling, add α-amylase to liquefy, filter with double-layer gauze, add corn steep liquor, dilute to volume, and divide into Erlenmeyer flasks, Sterilize at a temperature of 118-122°C for 20-25 minutes, inoculate after cooling, and cultivate at a temperature of 32-35°C for 20-30 hours on a rotary shaker at 120-220r/min to obtain seeds. (3) Shake flask fermentation Fermentation process without feeding Add water to the starchy raw material of the fermentation medium to gelatinize, liquefy, filter, and finally add corn steep liquor, adjust the pH, constant volume, divide into conical flasks, sterilize at 118-122°C for 20-30 minutes, and cool , add the cultivated seed culture according to the inoculum amount of 10-20%, and then cultivate it on a 120-220r/min rotary shaker at a temperature of 30-32°C for 3-4 days to obtain a fermentation liquid product, (4) Shake flask fermentation Fed-batch fermentation process The preparation of the fermented base material medium is the same as the fermentation medium described in the non-feeding fermentation process above. The base medium is divided into Erlenmeyer flasks, sterilized at a temperature of 118-122°C for 20-30min, and after cooling, press 10~ Add 20% of the inoculum to the cultured seeds, and feed the culture medium on a 120-220r/min rotary shaker with 10-20% feed 1-3 times each time, only the concentration of carbon source It is 3-5 times that of the base material, and the other ingredients are the same. It is cultivated at 30-32°C for 4-6 days to obtain the fermentation liquid product. (5) Enzyme Extraction Put the above-mentioned fermentation liquid product into a centrifuge, centrifuge at 3000-3500rpm for 10-20 minutes, wash, and filter and combine the supernatant to obtain a crude enzyme solution. Obtain concentrated enzyme solution at -45°C, adjust the pH of the concentrated enzyme solution to 3.5-4.5, add 10-20g of corn starch per liter of enzyme solution, stir evenly, so that the enzyme and starch are fully adsorbed, slowly at a temperature of 10-20°C Add 2-2.5 times of refrigerated ethanol, stir while adding, and you can see the precipitation of the enzyme. After the sediment is centrifuged, the obtained enzyme sludge is placed in a vacuum drying box, and the vacuum degree is 0.07-0.09Mpa, the temperature is 40-45 ℃ drying for 3-4 hours to obtain the finished crude enzyme preparation, 3. The use of the acid-resistant liquefaction saccharification enzyme according to claim 1, characterized in that the liquefaction saccharification enzyme is used for starch hydrolysis in starch sugar production and starch hydrolysis in alcohol, amino acid, organic acid and antibiotic fermentation industries.